1. Field of the Invention
The present invention relates to a portable information terminal, and more particularly to a bi-directional detector, which enable a host and a client in a collection terminal connected to various function expanding devices, to detect each other.
2. Description of the Related Art
As wireless communication spreads and requests for mobile computing enabled by this spread of the wireless communication increase, a collection terminal has been developed for connecting a portable information terminal, such as a portable telephone or a personal digital assistant (PDA), to various devices. This development has expanded the functions of the collection terminal. A control module of the collection terminal used for controlling each of the devices is defined as a client and a control module for synthetically managing the clients is defined as a hostpart.
FIGS. 1A and 1B are block diagrams illustrating the concept of a collection terminal. FIG. 1A is a block diagram showing a general collection terminal. Referring to FIG. 1A, the general collection terminal includes one host part 11 and a plurality of clients 13 to 17 connected to the host part 11. FIG. 1B is a block diagram showing a collection terminal used as a telematics unit for vehicles. Referring to FIG. 1B, the collection terminal includes a charging unit 23, an audio unit 25, a navigation processing unit 27, a hands-free unit 29, and a control unit 21, which synthetically manages these units 23-29. In FIG. 1b, the control unit 21 operates as a host part of the collection terminal. Further, the charging unit 23, the audio unit 25, the navigation processing unit 27, and the hands-free unit 29 operate as clients for controlling corresponding devices.
In the conventional collection terminals having described above constructions, the host part receiving a connection request signal (hereinafter, referred to as an REQ) from the client, transmits an acknowledgment signal (hereinafter, referred to as an ACK) to the client, so that the client and the host part are connected to each other.
FIGS. 2A and 2B are flowcharts illustrating methods by which a host part of a collection terminal detects a client. Specifically, FIG. 2A is a flowchart illustrating a method by which the host part 11 of the collection terminal in FIG. 1A detects connections of the clients 13, 15, and 17 and responds to the detection. FIG. 2B is a flowchart illustrating a method by which the control unit 21 in FIG. 1B detects connections of the navigation processing unit 27, and the hands-free unit 29 and responds to the detection.
Referring to FIG. 2A, in step S31 the host part 11 receives a REQ from the client 13 and transmits an ACK with respect to the REQ of the client 13 in step S32. The host part 11, in step S33 receives a REQ from the client 15 and transmits an ACK with respect to the REQ of the client 15 in step S34. In step S36, the host part 11 receives a REQ from the client 17 and transmits an ACK with respect to the REQ of the client 17 in step S36. Accordingly, as the types and number of devices added to the collection terminal increases, the host part 11 must respond to a connection request for other devices while simultaneously controlling each device. Therefore, a system becomes overloaded.
Referring to FIG. 2B, in step S41 the control unit 21 receives a REQ from a navigation processing unit 27, transmits an ACK with respect to the REQ of the navigation processing unit 27 in step S42, and then starts an operation of the navigation processing unit 27 in step S43. As described above, when in step S44 the control unit 21 receives a REQ from another client, e.g., the hands-free unit 29 while performing its heavy load, such as a navigation operation in step S43, the control unit 21 cannot immediately respond. That is, after a predetermined delay time in step S45, the control unit 21 transmits an ACK to the hands-free unit 29 in step S46, because the control unit 21 spends system resources on the job which requires a heavy processing, such as management of the operation of the navigation processing unit 27.
FIG. 3 is a block diagram schematically showing a conventional client detector. Referring to FIG. 3, the client detector includes a host part 50 and a client 60. The host part 50 includes a client detection unit 51, a client identification unit 53, and a first interface unit (hereinafter, referred to as an I/F) 55. The client 60 includes a second interface unit (hereinafter, referred to as an I/F) 61.
The client or second I/F 61 forms a communication channel with the host or first I/F 55, transmits a REQ of the client 60 to the host part 50, and receives an ACK from the host part 50.
Meanwhile, the first I/F 55 receives the REQ of the client 60 from the second I/F 61 to transmit the received REQ to the client detection unit 51 and the client identification unit 53, and transmits an ACK for the REQ to the client 60.
The client detection unit 51 detects the client 60 in the client section on the basis of the REQ received through the first I/F 55, and the client identification unit 53 identifies the type of the detected client 60 in the client section.
In the conventional method described above, the host part responds to a REQ of each client. Accordingly, when a central processing unit (hereinafter, referred to as a CPU) of the host part is overloaded due to implementation of a predetermined operation, a response of the host part to the REQ of the client is delayed. As a result, a delay occurs when the client detects a connection with the host part and reacts to the detection.
Also, the client must periodically check a connection with the host part through a communication channel even after a connection has been already performed as well as in an initial connection step with the host part. Accordingly, a CPU overload, in responding to the clients' requests, occurs in the host part. This CPU overload in the host part causes the response delay by the client.